Clinician-Driven Test Development Supports Comprehensive Drug Panels
Clinician-Driven Test Development Supports Comprehensive Drug Panels
Featured in Pathology Today: Winter/Spring 2017 Edition
Pain management drugs and benzodiazepines are among the most prescribed medications, and they are also the most abused classes of prescription drugs.1-3 Patients enrolled in pain management programs must be monitored for compliance, which means appropriate use of prescribed drugs and abstinence from non-prescribed drugs.
Laboratory medicine supports this public health effort with comprehensive panels that detect and measure the presence of a number of drugs or their metabolites in the patient’s urine. Although opioid medications such as fentanyl, oxycodone (OxyContin, Percocet), and hydrocodone (Vicodin) are often targeted, benzodiazepines such as diazepam (Valium) and alprazolam (Xanax) also have a high risk for abuse or other negative interactions, and they should be monitored as well.
At Cleveland Clinic’s Robert J. Tomsich Pathology & Laboratory Medicine Institute (RT-PLMI), the development of these panels has been guided by active collaboration between laboratory medical and administrative staff and practicing physicians from a variety of fields, including pain management, addiction and recovery, and behavioral health. Representing RT-PLMI in this interdisciplinary work group are:
• Courtney Heideloff, family health center supervisor
• Drew Payto, supervisor of special chemistry
This innovative clinician-driven model seeks to develop tests that are the most appropriate and cost effective tests for the specific drugs that physicians encounter in regular clinical practice, without performing unnecessary or duplicative procedures. As described by Xavier Jimenez, MD, director of the Chronic Pain Rehabilitation Program in Cleveland Clinic’s Neurological Institute and one of the practitioners in the group, “How can we maximize the laboratory’s resources, personnel, and procedures to help what we’re doing clinically?”
The Need for Comprehensive Testing
A 2012 National Health Interview Study found that 25.5 million adults reported suffering from chronic or daily pain, and 39.8 million adults (or 17.6% of all adults) had recently experienced category 3 or 4 pain, the highest levels on the study’s scale.4 The same year, there were 259 million prescriptions for opioid pain relievers written in the United States, following a 7.3% increase in prescription rate from 2007.5
Benzodiazepines are widely prescribed to treat anxiety, sleep disorders, seizures, or muscle spasms. In 2008, approximately 75 million benzodiazepine prescriptions were filled in the United States.3
Laboratory testing helps maintain patient safety when prescribing these powerful medications. In addition to the potential for addiction with both opioids and benzodiazepines, these classes of drugs also should not be taken together, as their combined use greatly increases the risk of respiratory depression and other serious complications. To safeguard against this dangerous combination, clinicians treating patients on an opioid pain management program may also run a panel to check for benzodiazepines, or vice versa.
“We want to give the appropriate medications for patients who are in pain and need treatment, and we need to do it carefully to maintain patient safety,” says Beth Minzter, MD, medical director for Pain Management for Cleveland Clinic main campus and a staff physician in the Anesthesiology Institute. For several years, Dr. Minzter has worked with Dr. Wang and his group on these tests to meet the needs of pain management programs. “Clinicians want to prescribe as safely as possible, and these tests help us make the best clinical decisions for our patients.”
Narrowing the Field
With dozens of opioid and benzodiazepine medications on the market, it is crucial to narrow the number of analytes. Limiting the number of substances being targeted in each panel helps contain costs and turnaround times—an important consideration for tests that often require being reordered periodically for compliance in pain management or rehabilitation programs. A leaner list also improves ease of use and clinical interpretation of test results.
“We knew that if the tests were overly complex or expensive, they wouldn’t be used. Making the tests clinically useful was our primary goal,” explains David Streem, MD, medical director of the Alcohol and Drug Recovery Center at Cleveland Clinic Lutheran Hospital. Dr. Streem has also worked with RT-PLMI on drug test development.
With this in mind, the developers focused on the drugs that are most commonly used or abused in a treatment or rehabilitation setting, relying heavily on the practical experience of the clinicians in the group. Likewise, Dr. Wang and Dr. McShane advised on the chemistry involved in testing a multiplicity of related analytes.
The combination of laboratory science and clinical practice helped reconcile the broad scope of what is scientifically possible with what is most clinically useful. After much informed discussion, the pain management panel was limited to 11 prescription medications (and related metabolites) and 5 illegal drugs, and the benzodiazepine panel was honed down to 7 medications.
Quantitative Pain Panel Analytes
• Methadone and metabolite (EDDP)
• Fentanyl and metabolite (Norfentanyl)
• Tramadol and metabolite (O-Desmethyltramadol)
• Buprenorphine and metabolite (Norbuprenorphine)
• Cocaine metabolite (Benzoylecgonine)
• Heroin metabolite (6-Acetylmorphine)
• Marijuana metabolite (THCA)
Benzodiazepine Panel Analytes
Table. List of analytes in pain management and benzodiazepine panels.
The methodologies selected for comprehensive drug panels also have a definite impact on the amount of information that clinicians can gain from the tests.
For analysis, providers may initially consider immunoassays because of their quick turnaround, convenience, and relatively low cost, but this testing method has several critical limitations. Immunoassays may lack the needed analytical sensitivity and/or specificity.6,7 For opioids, most immunoassay tests cannot distinguish between various specific drugs and cannot detect oxymorphone at all.8,9 For benzodiazepines, most immunoassay tests have unacceptable false-negative and false-positive rates for various benzodiazepines.10 In addition, immunoassays are commonly only semi-quantitative, and clinicians in some cases need quantitative assessment of urine drug concentrations.8
In practice, the limitations of immunoassays can translate into serious consequences for patients. “In recovery programs, lab tests are used to prove patients’ treatment success and sobriety, and a false positive can bring that all into question,” says Dr. Streem. “For many patients, there’s a lot at stake.”
Additionally, certain drugs may actually be prescribed as part of a treatment plan, such as buprenorphine which may be used to treat opioid addiction. A qualitative immunoassay may not allow the provider to determine whether the substance detected in the patient’s urine is an appropriately prescribed medication or some related drug that is prohibited.
In contrast to immunoassays, high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) offers high resolving power, high selectivity, and wide dynamic range, all of which enable simultaneous quantification of a broad spectrum of drugs present in biological matrices.8 Recent research recommends the use of LC-MS/MS to measure opioids and benzodiazepines due to the method’s high sensitivity and specificity.11,12
Another consideration is the hydrolysis method used to convert drugs conjugated with glucuronide in urine specimens back into free drugs. The conjugation rate varies significantly within and among patients, and so conjugated drugs are usually converted to free drugs prior to analysis for more consistent results. This includes opiates such as such as morphine and codeine, or benzodiazepines such as oxazepam, lorazepam, and temazepam.
Chemical hydrolysis is efficient but may result in unwanted reactions. For example, acid hydrolysis can cause structural changes to various benzodiazepines, leading to a loss of compound information which can obscure the original benzodiazepine.13 In contrast, enzymatic hydrolysis is much milder and is better at identifying the original drug, but it needs longer incubation times to achieve sufficient hydrolysis efficiency.
Interpretation and Communication
Even with drug panels designed for simplicity and accuracy, the complexity of factors affecting the test’s results may make interpretation more challenging than a simple positive/negative test. For example, the level of drugs or metabolites discovered in urine can vary due to many factors, including dosage, the patient’s individual metabolic rate and hydration status, and the relative time between drug use and collection of the urine sample. The presence of other medications or substances, prescribed or otherwise, can also affect test results.
For pain management and benzodiazepine panels at Cleveland Clinic, results are provided in a detailed report with interpretive comments written by laboratory staff who are knowledgeable of the chemistry involved in each analyte as well as any possible interactions. Additional consultative support for results interpretation is available as needed.
“In a clinical setting, interpreting someone’s test results isn’t always straightforward,” says Dr. Streem, who often has to try to deduce a patient’s usage behavior from the quantitative values in the test report. “If I have questions about the results, laboratory staff are always available to help understand the nuances of the test.”
Dr. Minzter echoes this sentiment, adding, “Dr. Wang and his staff in RT-PLMI are excellent at explaining test results and putting them into proper context. We can use the objective data from these tests and make informed, independent clinical decisions for our patients.”
Putting Patient Success First
Although drug panels are usually performed to monitor possible abuse or diversion of drugs, clinicians emphasize the value of testing in contributing to the patient’s treatment success. Accurate and objective test results, expert interpretation, and informed clinical decision-making allow patients who are appropriately using prescription medications to continue doing so. That means that Dr. Jimenez and Dr. Streem’s patients can continue participating and making progress in their recovery programs, and physicians such as Dr. Minzter can continue prescribing the appropriate medications that bring relief to patients who are in great pain.
This focus on patient success has made the development of these tests a positive, productive process. As Dr. Wang in RT-PLMI notes, “This has been one of the best experiences. Everyone has been engaged, with a unified purpose.”
By incorporating clinicians from a variety of institutional backgrounds into the test development process, these comprehensive panels have been developed with a distinct appreciation for how drug tests are used in daily practice and how they can have a significant impact on a patient’s treatment success.
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